(added in 1.1 - 2014 March)[Optional but not optional for Outlook] This replaces CapabilitiesSet=MailBoxThe minimum set of javascript API requirements that your addin needs.Specifying a requirement set does not limit the available APIs that the add-in can use. If an add-in specifies 1.1 but is running in an Outlook client that supports 1.3 then APIs from 1.3 can be used.